'osmosis' is a special kind of diffusion comment

Diffusion is process from one part of the cell to the other, or from cell to cell, or over short distances, say, from the inter- cellular spaces of the leaf to the outside. No energy expenditure takes place. In diffusion, molecules move in a random fashion, the net result being substances moving from regions of higher concentration to regions of lower concentration. Diffusion is a slow process and is not dependent on a ‘living system’. It is generally observed in both gases and liquids.

Osmosis is the term used to refer specifically to the diffusion of water across a differentially- or semi-permeable membrane. Osmosis occurs spontaneously in response to a driving force. The net direction and rate of osmosis depends on both the pressure gradient and concentration gradient. Water will move from its region of higher chemical potential (or concentration) to its region of lower chemical potential until equilibrium is reached. So, osmosis is the special case of diffusion.

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Osmosis is diffusion through a semi-permeable membrane. Diffusion can take place in all three states (solids, liquid and gases) but osmosis takes place only in liquids.And in diffusion, the movement of either solute or solvent occurs in both directions whereas in osmosis, there is only unidirectional flow of solvent. Therefore, osmosis is a special kind of diffusion.


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